I have to agree with Sephi. I don't think those games are blatently trying to brainwash us, but they certainly try to influence us. Military endorsements and adds going along with such games in magazines and websites and the like only help to support this.
They aren't bad games (except I think Rainbow six sucks... too complicated of controls), but you cannot deny that the military does have a hand in these games for multiple reasons. They use them to train their soldiers, and I also think that they're used to familiarize average people with the concepts and skills required in war.
America is a very war-like country (anyone who denies this is deluding themselves), and also very media based. It makes sense for the military to plant the seeds of war into our youth. But that really isn't the point. These military sims, (not wargames, but sims) are indirectly training us for war. So I can see the OP's point, but none of that means an average person will play a war sim and go throw a grenade through their neighbors window!
Just trying to say that war sims are just that, they simulate war and therefore are indirectly training us. That said, they DO NOT brainwash us or force us to go out and kill people. Although these type of games may influence someone to join the military, it won't make them go out and commit mass murder in the name of war.